Janesville Illinois Climate Data

Monthly Average Climate Data for Janesville Illinois

Switch Data to Celsius/Metric Units
MonthAvg. LowAvg. HighAvg. Precip
January20.2 °F36.2 °F2.73 in.
February23.1 °F40.9 °F2.38 in.
March32.1 °F52.0 °F3.03 in.
April42.9 °F64.8 °F4.72 in.
May54.1 °F74.7 °F4.5 in.
June63.0 °F83.2 °F4.89 in.
July65.8 °F86.4 °F4.3 in.
August63.7 °F85.2 °F3.02 in.
September56.0 °F79.7 °F3.11 in.
October44.6 °F67.4 °F3.52 in.
November34.0 °F52.8 °F3.66 in.
December25.5 °F40.8 °F2.68 in.
Annual43.8 °F63.7 °F42.54 in.

Climate Data for Janesville Illinois

Average First Frost DateOct. 11 - Oct. 20
Average Last Frost DateMay 1 - May 10
Average Days With Frost100-125 Days
Plant Hardiness Zone - 2023Zone 6a : -10°F to -5°F
Plant Hardiness Zone - 2012Zone 6a : -10°F to -5°F
Current Drought ConditionsModerate Drought
Köppen Climate ClassificationDfa - Humid Continental Hot Summers With Year Around Precipitation
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